When light is coupled to a photonic integrated circuit (PIC) after propagating through a single mode optical fiber, the polarization state of the optical mode will typically be of an unknown and uncontrolled polarization. Many components in a PIC have polarization-dependent behavior, meaning the component will have a different transfer function for the different polarization modes (e.g., TE0, TM0).
A polarization diversity approach in a PIC describes when TE0 and TM0 components of received light are split and then processed separately. To accomplish the diversity approach, a component is required to split the TE0 and TM0 modes into different waveguides. A desirable feature in a polarization diversity approach is that two circuits that process the two input polarizations may be of identical design. For this to be possible a component is required to rotate light, in other words convert it from a TE0 mode to a TM0 mode or vice versa. Current solutions that enable this splitting and rotation in waveguides require separate devices for each function, thereby increasing the cost and manufacturing complexity of the PIC.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.